Do not follow the practices of the land of Egypt, where you used to live, or follow the practices of the land of Canaan, where I am bringing you. You must not follow their customs. – Leviticus 18:3
As a missionary, I learned that it is often a good idea to try to assume some of the cultural practices of the people whom you seek to reach. Some, but not all.
God instructed Israel to leave behind the pagan practices of their former home (Egypt) and to also refrain from following the pagan practices where they were headed (Canaan). He wanted the Israelites to live according to His principles, not those adopted by the prevailing cultural environment. They were His chosen people and He wanted everyone to see the distinction.
In the same manner, He has instructed us (His Body, His Church, His missionaries) to do the same. We all come from a past that we need to abandon in order that we might impact the “land” in which we now live. The question is, will we influence it or will it change us?
I guess it depends on whose “customs” we follow.
I have but one passion – it is He, it is He alone. The world is the field and the field is the world; and henceforth that country shall be my home where I can be most used in winning souls for Christ. – Count Ludwig Von Zinzindorf